U.S. patent application number 16/707131 was filed with the patent office on 2021-06-10 for method for operating a vehicle having a torque converter.
The applicant listed for this patent is Ford Global Technologies, LLC. Invention is credited to Sassan Farahmand, Patrick Soderborg, Fazal Urrahman Syed, William David Treharne.
Application Number | 20210171006 16/707131 |
Document ID | / |
Family ID | 1000004537789 |
Filed Date | 2021-06-10 |
United States Patent
Application |
20210171006 |
Kind Code |
A1 |
Syed; Fazal Urrahman ; et
al. |
June 10, 2021 |
METHOD FOR OPERATING A VEHICLE HAVING A TORQUE CONVERTER
Abstract
A method for operating a vehicle that includes a torque
converter is described. In one example, the method adjusts torque
of an electric machine in response to a requested torque converter
speed. The requested torque converter speed linearizes torque
output of a torque converter so that vehicle wheel torque control
may be improved.
Inventors: |
Syed; Fazal Urrahman;
(Canton, MI) ; Treharne; William David;
(Ypsilanti, MI) ; Soderborg; Patrick; (Dexter,
MI) ; Farahmand; Sassan; (Canton, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ford Global Technologies, LLC |
Dearborn |
MI |
US |
|
|
Family ID: |
1000004537789 |
Appl. No.: |
16/707131 |
Filed: |
December 9, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B60W 20/13 20160101;
B60W 2510/0233 20130101; B60W 10/026 20130101; F16D 33/18 20130101;
B60W 2540/10 20130101; B60W 2710/083 20130101; F16H 61/50 20130101;
B60W 2710/0666 20130101; F16D 39/00 20130101 |
International
Class: |
B60W 10/02 20060101
B60W010/02; F16D 33/18 20060101 F16D033/18; F16D 39/00 20060101
F16D039/00 |
Claims
1. A vehicle operating method, comprising: generating a torque
converter speed ratio in response to a torque converter turbine
torque request and a measured torque converter turbine speed; and
adjusting a torque of an electric machine via a controller in
response to a requested torque converter impeller speed that is
based on the torque converter speed ratio.
2. The method of claim 1, where the torque of the electric machine
is adjusted via a proportional/integral controller, and where the
torque converter speed ratio is generated in further response to a
transmission fluid temperature.
3. The method of claim 1, further comprising determining the
requested torque converter impeller speed via dividing the measured
torque converter turbine speed by the torque converter speed
ratio.
4. The method of claim 3, further comprising referencing the torque
converter map via the torque converter turbine torque request, the
transmission fluid temperature, and an actual torque converter
turbine speed to generate the torque converter speed ratio.
5. The method as claimed in claim 4, further comprising generating
the torque converter turbine torque request via a torque converter
turbine torque map.
6. The method of claim 5, further comprising referencing the torque
converter turbine torque map via accelerator pedal position.
7. The method of claim 1, further comprising limiting a rate of
change of the requested torque converter impeller speed.
8. A vehicle system, comprising: an electric machine; a torque
converter coupled to the electric machine and a step ratio
transmission; a controller including executable instructions stored
in non-transitory memory to cause the controller to generate a
torque converter speed ratio from a torque converter map that is
referenced via a torque converter turbine torque request and an
estimated torque converter turbine speed, and additional
instructions to adjust a speed of the electric machine according to
the torque converter speed ratio.
9. The vehicle system of claim 8, further comprising additional
instructions to generate a torque converter impeller speed request
via dividing the estimated torque converter turbine speed by the
torque converter speed ratio.
10. The vehicle system of claim 9, further comprising additional
instructions to generate the torque converter turbine torque
request from an accelerator pedal position.
11. The vehicle system of claim 10, where the torque converter
turbine torque request is generated via a torque converter turbine
torque map, and where the torque converter map is also referenced
via a transmission fluid temperature.
12. The vehicle system of claim 11, further comprising additional
instructions to limit a rate of change of the torque converter
impeller speed request.
13. The vehicle system of claim 11, further comprising additional
instructions to generate a torque converter impeller speed request
error via subtracting an actual speed of the electric machine from
the torque converter impeller speed request.
14. The vehicle system of claim 11, further comprising additional
instructions to apply a proportional/integral controller to the
torque converter impeller speed request error.
15. A vehicle operating method, comprising: generating a torque
converter speed ratio in response to a torque converter turbine
torque request and a measured torque converter turbine speed;
adjusting a torque of an electric machine via a controller in
response to a requested torque converter impeller speed that is
based on the torque converter speed ratio; and adjusting an engine
torque in response to an error between a requested electric energy
storage device discharge power and an actual electric energy
storage discharge power.
16. The method of claim 15, where the requested electric energy
storage device discharge power is a function of accelerator pedal
position and state of charge of an electric energy storage device,
and where the torque converter speed ratio is generated in further
response to a transmission fluid temperature.
17. The method of claim 15, further comprising applying a
proportional/integral controller to the error between the requested
electric energy storage device discharge power and the actual
electric energy storage discharge power.
18. The method of claim 15, where the actual electric energy
storage discharge power is based on adjusting the torque of the
electric machine.
19. The method of claim 15, further comprising adjusting the torque
of the electric machine in response to accelerator pedal
position.
20. The method of claim 15, further comprising adjusting the torque
of the electric machine in response to transmission fluid
temperature.
Description
FIELD
[0001] The present description relates to methods and a system for
operating a vehicle that includes a torque converter. The methods
and systems may reduce a non-linear axle torque response to an
accelerator input.
BACKGROUND AND SUMMARY
[0002] A vehicle may include a torque converter to smooth torque
that is delivered from an engine to an automatic transmission. The
torque converter also allows the engine to rotate at idle speed
without the vehicle having to move. Torque that is input to the
torque converter's impeller may be multiplied when the torque
converter's clutch is open and when torque converter impeller speed
is different than torque converter impeller speed. However, the
torque converter's torque multiplication is non-linear such that a
change in accelerator pedal position may not always result in a
same proportional change in axle torque. For example, a torque that
is input to a torque converter impeller may result in a first
torque converter turbine torque when torque converter impeller
speed is a first speed. The same torque that is input to the torque
converter impeller may result in a second torque converter turbine
torque when torque converter impeller speed is a second speed.
Consequently, it may be difficult for a human driver to regulate
axle torque during low vehicle speed conditions. Difficulty in
regulating axle torque may be particularly noticeable while
operating a vehicle off-road where driving surfaces may change
significantly in a short distance of travel. Therefore, it may be
desirable to provide a way of compensating for the torque
converter's non-linear response so that human drivers may find
vehicle wheel torque regulation easier at low vehicle speeds.
[0003] The inventors herein have recognized the above-mentioned
issues and have developed a vehicle operating method, comprising:
generating a torque converter speed ratio in response to a torque
converter turbine torque request, an transmission fluid
temperature, and a measured torque converter turbine speed; and
adjusting a torque of an electric machine via a controller in
response to a requested torque converter impeller speed that is
based on the torque converter speed ratio.
[0004] By generating a torque converter speed ratio in response to
a torque converter turbine torque request, a transmission fluid
temperature, and a measured or estimated torque converter turbine
speed, it may be possible to provide the technical result of
linearizing torque output of a driveline via adjusting a torque of
an electric machine in response to a requested torque converter
impeller speed that is based on the torque converter speed ratio.
In particular, the difference between a requested torque converter
impeller speed and an actual torque converter impeller speed may be
reduced so that an accelerator pedal position generates a unique
and repeatable torque converter turbine torque that may be
delivered to vehicle wheels even during conditions of varying
transmission fluid temperature and actual turbine speed. This
contrasts with an accelerator pedal position that is used to
generate a propulsion source torque that may be modified in many
different ways via the torque converter to generate different
torque converter turbine torques, which may result in different
wheel torques.
[0005] The present description may provide several advantages.
Specifically, the approach may improve low speed vehicle launches.
The approach may also simplify vehicle control for human drivers.
In addition, the approach may reduce driveline torque disturbances,
thereby improving vehicle drivability.
[0006] The above advantages and other advantages, and features of
the present description will be readily apparent from the following
Detailed Description when taken alone or in connection with the
accompanying drawings.
[0007] It should be understood that the summary above is provided
to introduce in simplified form a selection of concepts that are
further described in the detailed description. It is not meant to
identify key or essential features of the claimed subject matter,
the scope of which is defined uniquely by the claims that follow
the detailed description. Furthermore, the claimed subject matter
is not limited to implementations that solve any disadvantages
noted above or in any part of this disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 shows a schematic diagram of an internal combustion
engine;
[0009] FIG. 2 shows a schematic diagram of an example vehicle
driveline or powertrain including the internal combustion engine
shown in FIG. 1;
[0010] FIG. 3 shows a block diagram of a method for controlling
driveline torque;
[0011] FIG. 4 shows a prior art example sequence of driveline
torque control;
[0012] FIG. 5 shows a driveline torque control sequence according
to the method of FIG. 3; and
[0013] FIG. 6 shows an example function for determining a torque
converter speed ratio from a turbine torque request that is
generated via an accelerator pedal.
DETAILED DESCRIPTION
[0014] The present description is related to operating a driveline
that has a torque converter. The torque converter may be positioned
in the driveline downstream of an engine and downstream of an
electric machine. The electric machine may provide torque to the
driveline when driver demand torque is low or when it may be
desirable to boost engine power. The driveline may include an
internal combustion engine of the type shown in FIG. 1. The engine
may be included in a driveline or powertrain as shown in FIG. 2.
The driveline may be operated according to the method shown in FIG.
3 to linearize a relationship between accelerator pedal position
and wheel torque that is delivered via a torque converter. A
driveline operating sequence according to the prior art is shown in
FIG. 4. A driveline operating sequence according to the method of
FIG. 3 is shown in FIG. 5 and an example function for determining a
requested or desired torque converter speed ratio is shown in FIG.
6. The desired torque converter speed ratio is used to determine a
desired torque converter impeller speed that generates a requested
torque converter impeller torque that is linear with accelerator
pedal position.
[0015] Referring to FIG. 1, internal combustion engine 10,
comprising a plurality of cylinders, one cylinder of which is shown
in FIG. 1, is controlled by electronic engine controller 12. Engine
10 is comprised of cylinder head 35 and block 33, which include
combustion chamber 30 and cylinder walls 32. Piston 36 is
positioned therein and reciprocates via a connection to crankshaft
40. Flywheel 97 and ring gear 99 are coupled to crankshaft 40.
Starter 96 (e.g., low voltage (operated with less than 30 volts)
electric machine) includes pinion shaft 98 and pinion gear 95.
Pinion shaft 98 may selectively advance pinion gear 95 to engage
ring gear 99. Starter 96 may be directly mounted to the front of
the engine or the rear of the engine. In some examples, starter 96
may selectively supply torque to crankshaft 40 via a belt or chain.
In one example, starter 96 is in a base state when not engaged to
the engine crankshaft.
[0016] Combustion chamber 30 is shown communicating with intake
manifold 44 and exhaust manifold 48 via respective intake valve 52
and exhaust valve 54. Each intake and exhaust valve may be operated
by an intake cam 51 and an exhaust cam 53. The position of intake
cam 51 may be determined by intake cam sensor 55. The position of
exhaust cam 53 may be determined by exhaust cam sensor 57. A phase
or position of intake valve 52 may be adjusted relative to a
position of crankshaft 40 via valve phase changing device 59. A
phase or position of exhaust valve 54 may be adjusted relative to a
position of crankshaft 40 via valve phase changing device 58. Valve
phase changing devices 58 and 59 may be electro-mechanical devices,
hydraulic devices, or mechanical devices.
[0017] Engine 10 includes a crankcase 39 that houses crankshaft 40.
Oil pan 37 may form a lower boundary of crankcase 39 and engine
block 33 and piston 36 may constitute an upper boundary of
crankcase 39. Crankcase 39 may include a crankcase ventilation
valve (not shown) that may vent gases to combustion chamber 30 via
intake manifold 44. Pressure in crankcase 39 may be sensed via
pressure sensor 38. Alternatively, pressure in crankcase 39 may be
estimated.
[0018] Fuel injector 66 is shown positioned to inject fuel directly
into cylinder 30, which is known to those skilled in the art as
direct injection. Fuel injector 66 delivers liquid fuel in
proportion to the pulse width from controller 12. Fuel is delivered
to fuel injector 66 by a fuel system (not shown) including a fuel
tank, fuel pump, and fuel rail (not shown). In one example, a high
pressure, dual stage, fuel system may be used to generate higher
fuel pressures.
[0019] In addition, intake manifold 44 is shown communicating with
turbocharger compressor 162 and engine air intake 42. In other
examples, compressor 162 may be a supercharger compressor. Shaft
161 mechanically couples turbocharger turbine 164 to turbocharger
compressor 162. Optional electronic throttle 62 adjusts a position
of throttle plate 64 to control air flow from compressor 162 to
intake manifold 44. Pressure in boost chamber 45 may be referred to
a throttle inlet pressure since the inlet of throttle 62 is within
boost chamber 45. The throttle outlet is in intake manifold 44. In
some examples, throttle 62 and throttle plate 64 may be positioned
between intake valve 52 and intake manifold 44 such that throttle
62 is a port throttle. Compressor recirculation valve 47 may be
selectively adjusted to a plurality of positions between fully open
and fully closed. Waste gate 163 may be adjusted via controller 12
to allow exhaust gases to selectively bypass turbine 164 to control
the speed of compressor 162. Air filter 43 cleans air entering
engine air intake 42.
[0020] Distributorless ignition system 88 provides an ignition
spark to combustion chamber 30 via spark plug 92 in response to
controller 12. Universal Exhaust Gas Oxygen (UEGO) sensor 126 is
shown coupled to exhaust manifold 48 upstream of catalytic
converter 70. Alternatively, a two-state exhaust gas oxygen sensor
may be substituted for UEGO sensor 126.
[0021] Converter 70 can include multiple catalyst bricks, in one
example. In another example, multiple emission control devices,
each with multiple bricks, can be used. Converter 70 can be a
three-way type catalyst in one example.
[0022] Controller 12 is shown in FIG. 1 as a conventional
microcomputer including: microprocessor unit 102, input/output
ports 104, read-only memory 106 (e.g., non-transitory memory),
random access memory 108, keep alive memory 110, and a conventional
data bus. Controller 12 is shown receiving various signals from
sensors coupled to engine 10, in addition to those signals
previously discussed, including: engine coolant temperature (ECT)
from temperature sensor 112 coupled to cooling sleeve 114; a
position sensor 134 coupled to an accelerator pedal 130 for sensing
force applied by human foot 132; a position sensor 154 coupled to
brake pedal 150 for sensing force applied by human foot 152, a
measurement of engine manifold pressure (MAP) from pressure sensor
122 coupled to intake manifold 44; an engine position sensor from a
Hall effect sensor 118 sensing crankshaft 40 position; a
measurement of air mass entering the engine from sensor 120;
cylinder pressure from pressure sensor 79; and a measurement of
throttle position from sensor 68. Barometric pressure may also be
sensed (sensor not shown) for processing by controller 12. In a
preferred aspect of the present description, engine position sensor
118 produces a predetermined number of equally spaced pulses every
revolution of the crankshaft from which engine speed (RPM) can be
determined.
[0023] During operation, each cylinder within engine 10 typically
undergoes a four stroke cycle: the cycle includes the intake
stroke, compression stroke, expansion stroke, and exhaust stroke.
During the intake stroke, generally, the exhaust valve 54 closes
and intake valve 52 opens. Air is introduced into combustion
chamber 30 via intake manifold 44, and piston 36 moves to the
bottom of the cylinder so as to increase the volume within
combustion chamber 30. The position at which piston 36 is near the
bottom of the cylinder and at the end of its stroke (e.g. when
combustion chamber 30 is at its largest volume) is typically
referred to by those of skill in the art as bottom dead center
(BDC).
[0024] During the compression stroke, intake valve 52 and exhaust
valve 54 are closed. Piston 36 moves toward the cylinder head so as
to compress the air within combustion chamber 30. The point at
which piston 36 is at the end of its stroke and closest to the
cylinder head (e.g. when combustion chamber 30 is at its smallest
volume) is typically referred to by those of skill in the art as
top dead center (TDC). In a process hereinafter referred to as
injection, fuel is introduced into the combustion chamber. In a
process hereinafter referred to as ignition, the injected fuel is
ignited by known ignition means such as spark plug 92, resulting in
combustion.
[0025] During the expansion stroke, the expanding gases push piston
36 back to BDC. Crankshaft 40 converts piston movement into a
rotational torque of the rotary shaft. Finally, during the exhaust
stroke, the exhaust valve 54 opens to release the combusted
air-fuel mixture to exhaust manifold 48 and the piston returns to
TDC. Note that the above is shown merely as an example, and that
intake and exhaust valve opening and/or closing timings may vary,
such as to provide positive or negative valve overlap, late intake
valve closing, or various other examples.
[0026] FIG. 2 is a block diagram of a vehicle 225 including a
powertrain or driveline 200. The powertrain of FIG. 2 includes
engine 10 shown in FIG. 1. Powertrain 200 is shown including
vehicle system controller 255, engine controller 12, electric
machine controller 252, transmission controller 254, energy storage
device controller 253, and brake controller 250. The controllers
may communicate over controller area network (CAN) 299. Each of the
controllers may provide information to other controllers such as
power output limits (e.g., power output of the device or component
being controlled not to be exceeded), power input limits (e.g.,
power input of the device or component being controlled not to be
exceeded), power output of the device being controlled, sensor and
actuator data, diagnostic information (e.g., information regarding
a degraded transmission, information regarding a degraded engine,
information regarding a degraded electric machine, information
regarding degraded brakes). Further, the vehicle system controller
255 may provide commands to engine controller 12, electric machine
controller 252, transmission controller 254, and brake controller
250 to achieve driver input requests and other requests that are
based on vehicle operating conditions.
[0027] For example, in response to a driver releasing an
accelerator pedal and vehicle speed, vehicle system controller 255
may request a desired wheel power or a wheel power level to provide
a desired rate of vehicle deceleration. The requested desired wheel
power may be provided by vehicle system controller 255 requesting a
first braking power from electric machine controller 252 and a
second braking power from engine controller 212, the first and
second powers providing a desired driveline braking power at
vehicle wheels 216. Vehicle system controller 255 may also request
a friction braking power via brake controller 250. The braking
powers may be referred to as negative powers since they slow
driveline and wheel rotation. Positive power may maintain or
accelerate driveline and wheel rotation.
[0028] Vehicle controller 255 and/or engine controller 12 may also
receive input from human/machine interface 256 and traffic
conditions (e.g., traffic signal status, distance to objects, etc.)
from sensors 257 (e.g., cameras, LIDAR, RADAR, etc.). In one
example, human/machine interface 256 may be a touch input display
panel. Alternatively, human/machine interface 256 may be a key
switch or other known type of human/machine interface.
Human/machine interface 256 may receive requests from a user. For
example, a user may request an engine stop or start via
human/machine interface 256. Additionally, human/machine interface
256 may display status messages and engine data that may be
received from controller 255.
[0029] In other examples, the partitioning of controlling
powertrain devices may be partitioned differently than is shown in
FIG. 2. For example, a single controller may take the place of
vehicle system controller 255, engine controller 12, electric
machine controller 252, transmission controller 254, and brake
controller 250. Alternatively, the vehicle system controller 255
and the engine controller 12 may be a single unit while the
electric machine controller 252, the transmission controller 254,
and the brake controller 250 are standalone controllers.
[0030] In this example, powertrain 200 may be powered by engine 10
and electric machine 240. In other examples, engine 10 may be
omitted. Engine 10 may be started with an engine starting system
shown in FIG. 1, via Belt-Driven Integrated Starter-Generator
(BISG) 219, or via driveline integrated starter/generator (ISG) 240
also known as an integrated starter/generator. A speed of BISG 219
may be determined via optional BISG speed sensor 203. Driveline ISG
240 (e.g., high voltage (operated with greater than 30 volts)
electrical machine) may also be referred to as an electric machine,
motor, and/or generator. Further, power of engine 10 may be
adjusted via torque actuator 204, such as a fuel injector,
throttle, etc.
[0031] BISG 219 is mechanically coupled to engine 10 via belt 231.
BISG 219 may be coupled to crankshaft 40 or a camshaft (e.g., 51 or
53 of FIG. 1). BISG 219 may operate as a motor when supplied with
electrical power via electric energy storage device 275 or low
voltage battery 280. BISG 219 may operate as a generator supplying
electrical power to electric energy storage device 275 or low
voltage battery 280. Bi-directional DC/DC converter 281 may
transfer electrical energy from a high voltage buss 274 to a low
voltage buss 273 or vice-versa. Low voltage battery 280 is
electrically coupled to low voltage buss 273. Electric energy
storage device 275 is electrically coupled to high voltage buss
274. Low voltage battery 280 may selectively supply electrical
energy to starter motor 96.
[0032] An engine output power may be transmitted to a first or
upstream side of powertrain disconnect clutch 235 through dual mass
flywheel 215. Disconnect clutch 236 is hydraulically actuated and
hydraulic pressure within driveline disconnect clutch 236
(driveline disconnect clutch pressure) may be adjusted via
electrically operated valve 233. The downstream or second side 234
of disconnect clutch 236 is shown mechanically coupled to ISG input
shaft 237.
[0033] ISG 240 may be operated to provide power to powertrain 200
or to convert powertrain power into electrical energy to be stored
in electric energy storage device 275 in a regeneration mode. ISG
240 is in electrical communication with energy storage device 275
via inverter 279. Inverter 279 may convert direct current (DC)
electric power from electric energy storage device 275 into
alternating current (AC) electric power for operating ISG 240.
Alternatively, inverter 279 may convert AC power from ISG 240 into
DC power for storing in electric energy storage device 275.
Inverter 279 may be controlled via electric machine controller 252.
ISG 240 has a higher output power capacity than starter 96 shown in
FIG. 1 or BISG 219. Further, ISG 240 directly drives powertrain 200
or is directly driven by powertrain 200. There are no belts, gears,
or chains to couple ISG 240 to powertrain 200. Rather, ISG 240
rotates at the same rate as powertrain 200. Electrical energy
storage device 275 (e.g., high voltage battery or power source) may
be a battery, capacitor, or inductor. The downstream side of ISG
240 is mechanically coupled to the impeller 285 of torque converter
206 via shaft 241. The upstream side of the ISG 240 is mechanically
coupled to the disconnect clutch 236. ISG 240 may provide a
positive power or a negative power to powertrain 200 via operating
as a motor or generator as instructed by electric machine
controller 252.
[0034] Torque converter 206 includes a turbine 286 to output power
to input shaft 270. Input shaft 270 mechanically couples torque
converter 206 to automatic transmission 208. Torque converter 206
also includes a torque converter bypass lock-up clutch 212 (TCC).
Power is directly transferred from impeller 285 to turbine 286 when
TCC is locked. TCC is electrically operated by controller 254.
Alternatively, TCC may be hydraulically locked. In one example, the
torque converter may be referred to as a component of the
transmission.
[0035] When torque converter lock-up clutch 212 is fully
disengaged, torque converter 206 transmits engine power to
automatic transmission 208 via fluid transfer between the torque
converter turbine 286 and torque converter impeller 285, thereby
enabling torque multiplication. In contrast, when torque converter
lock-up clutch 212 is fully engaged, the engine output torque is
directly transferred via the torque converter clutch to an input
shaft 270 of transmission 208. Alternatively, the torque converter
lock-up clutch 212 may be partially engaged, thereby enabling the
amount of power that is directly delivered to the transmission to
be adjusted. Torque converter turbine speed may be estimated or
measured via optional turbine position sensor 243, or
alternatively, via position sensor 272 and the presently engaged
transmission gear ratio. The transmission controller 254 may be
configured to adjust the amount of power transmitted by torque
converter 212 by adjusting the torque converter lock-up clutch in
response to various engine operating conditions, or based on a
driver-based engine operation request.
[0036] Torque converter 206 also includes pump 283 that pressurizes
fluid to operate disconnect clutch 236, forward clutch 210, and
gear clutches 211. Pump 283 is driven via impeller 285, which
rotates at a same speed as ISG 240.
[0037] Automatic transmission 208 includes gear clutches 211 and
forward clutch 210 for selectively engaging and disengaging forward
gears 213 (e.g., gears 1-10) and reverse gear 214. Automatic
transmission 208 is a fixed ratio transmission. Alternatively,
transmission 208 may be a continuously variable transmission that
has a capability of simulating a fixed gear ratio transmission and
fixed gear ratios. The gear clutches 211 and the forward clutch 210
may be selectively engaged to change a ratio of an actual total
number of turns of input shaft 270 to an actual total number of
turns of wheels 216. Gear clutches 211 may be engaged or disengaged
via adjusting fluid supplied to the clutches via shift control
solenoid valves 209. Power output from the automatic transmission
208 may also be relayed to wheels 216 to propel the vehicle via
output shaft 260. Specifically, automatic transmission 208 may
transfer an input driving power at the input shaft 270 responsive
to a vehicle traveling condition before transmitting an output
driving power to the wheels 216. Transmission controller 254
selectively activates or engages TCC 212, gear clutches 211, and
forward clutch 210. Transmission controller also selectively
deactivates or disengages TCC 212, gear clutches 211, and forward
clutch 210.
[0038] Further, a frictional force may be applied to wheels 216 by
engaging friction wheel brakes 218. In one example, friction wheel
brakes 218 may be engaged in response to a human driver pressing
their foot on a brake pedal (not shown) and/or in response to
instructions within brake controller 250. Further, brake controller
250 may apply brakes 218 in response to information and/or requests
made by vehicle system controller 255. In the same way, a
frictional force may be reduced to wheels 216 by disengaging wheel
brakes 218 in response to the human driver releasing their foot
from a brake pedal, brake controller instructions, and/or vehicle
system controller instructions and/or information. For example,
vehicle brakes may apply a frictional force to wheels 216 via
controller 250 as part of an automated engine stopping
procedure.
[0039] In response to a request to accelerate vehicle 225, vehicle
system controller may obtain a driver demand torque or torque
request from an accelerator pedal or other device. Vehicle system
controller 255 then allocates a fraction of the requested driver
demand torque to the engine and the remaining fraction to the ISG
or BISG. Vehicle system controller 255 requests the engine torque
from engine controller 12 and the ISG power from electric machine
controller 252. If the ISG torque plus the engine torque is less
than a transmission input torque limit (e.g., a threshold value not
to be exceeded), the torque is delivered to torque converter 206
which then relays at least a fraction of the requested torque to
transmission input shaft 270. Transmission controller 254
selectively locks torque converter clutch 212 and engages gears via
gear clutches 211 in response to shift schedules and TCC lockup
schedules that may be based on input shaft power and vehicle speed.
In some conditions when it may be desired to charge electric energy
storage device 275, a charging power (e.g., a negative ISG power)
may be requested while a non-zero driver demand power is present.
Vehicle system controller 255 may request increased engine torque
to overcome the charging power to meet the driver demand power.
[0040] Accordingly, power control of the various powertrain
components may be supervised by vehicle system controller 255 with
local power control for the engine 10, transmission 208, electric
machine 240, and brakes 218 provided via engine controller 12,
electric machine controller 252, transmission controller 254, and
brake controller 250.
[0041] As one example, an engine torque output may be controlled by
adjusting a combination of spark timing, fuel pulse width, fuel
pulse timing, and/or air charge, by controlling throttle opening
and/or valve timing, valve lift and boost for turbo- or
super-charged engines. In the case of a diesel engine, controller
12 may control the engine torque output by controlling a
combination of fuel pulse width, fuel pulse timing, and air charge.
Engine braking torque or negative engine torque may be provided by
rotating the engine with the engine generating power that is
insufficient to rotate the engine. Thus, the engine may generate a
braking torque via operating at a low power while combusting fuel,
with one or more cylinders deactivated (e.g., not combusting fuel),
or with all cylinders deactivated and while rotating the engine.
The amount of engine braking power may be adjusted via adjusting
engine valve timing. Engine valve timing may be adjusted to
increase or decrease engine compression work. Further, engine valve
timing may be adjusted to increase or decrease engine expansion
work. In all cases, engine control may be performed on a
cylinder-by-cylinder basis to control the engine power output.
[0042] Electric machine controller 252 may control power output and
electrical energy production from ISG 240 by adjusting current
flowing to and from field and/or armature windings of ISG 240 as is
known in the art.
[0043] Transmission controller 254 receives torque converter
impeller position via position sensor 271. Transmission controller
254 may convert torque converter impeller position into torque
converter impeller speed via counting a number of known angular
distance pulses over a predetermined time interval. Controller 254
may count shaft position pulses via position sensor 272 over a
predetermined time interval to determine transmission output shaft
velocity. Transmission controller 254 may also differentiate
transmission output shaft velocity to determine transmission output
shaft acceleration. Transmission controller 254, engine controller
12, and vehicle system controller 255, may also receive addition
transmission information from sensors 277, which may include but
are not limited to pump output line pressure sensors, transmission
fluid temperature sensors, transmission hydraulic pressure sensors
(e.g., gear clutch fluid pressure sensors), ISG temperature
sensors, and BISG temperatures, gear shift lever sensors, and
ambient temperature sensors. Transmission controller 254 may also
receive requested gear input from gear shift selector 290 (e.g., a
human/machine interface device). Gear shift selector 290 may
include positions for gears 1-X (where X is an upper gear number),
D (drive), neutral (N), and P (park). Shift selector 290 shift
lever 293 may be prevented from moving via a solenoid actuator 291
that selectively prevents shift lever 293 from moving from park or
neutral into reverse or a forward gear position (e.g., drive).
[0044] Brake controller 250 receives wheel speed information via
wheel speed sensor 221 and braking requests from vehicle system
controller 255. Brake controller 250 may also receive brake pedal
position information from brake pedal sensor 154 shown in FIG. 1
directly or over CAN 299. Brake controller 250 may provide braking
responsive to a wheel power command from vehicle system controller
255. Brake controller 250 may also provide anti-lock and vehicle
stability braking to improve vehicle braking and stability. As
such, brake controller 250 may provide a wheel power limit (e.g., a
threshold negative wheel power not to be exceeded) to the vehicle
system controller 255 so that negative ISG power does not cause the
wheel power limit to be exceeded. For example, if controller 250
issues a negative wheel power limit of 50 N-m, ISG power is
adjusted to provide less than 50 N-m (e.g., 49 N-m) of negative
power at the wheels, including accounting for transmission
gearing.
[0045] Thus, the system of FIGS. 1 and 2 provides for a vehicle
system, comprising: an electric machine; a torque converter coupled
to the electric machine and a step ratio transmission; a controller
including executable instructions stored in non-transitory memory
to cause the controller to generate a torque converter speed ratio
from a torque converter map that is referenced via a torque
converter turbine torque request, transmission fluid temperature,
and an estimated torque converter turbine speed, and additional
instructions to adjust a speed of the electric machine according to
the torque converter speed ratio. The vehicle system further
comprises additional instructions to generate a torque converter
impeller speed request via dividing the estimated torque converter
turbine speed by the torque converter speed ratio. The vehicle
system further comprises additional instructions to generate the
torque converter turbine torque request from an accelerator pedal
position. The vehicle system includes where the torque converter
turbine torque request is generated via a torque converter turbine
torque map. The vehicle system further comprises additional
instructions to limit a rate of change of the torque converter
impeller speed request. The vehicle system further comprises
additional instructions to generate a torque converter impeller
speed request error via subtracting an actual speed of the electric
machine from the torque converter impeller speed request. The
vehicle system further comprises additional instructions to apply a
proportional/integral controller to the torque converter impeller
speed request error.
[0046] Referring now to FIG. 3, a block diagram 300 of a method for
operating a vehicle is shown. At least portions of method 300 may
be implemented as executable controller instructions stored in
non-transitory memory. Method 300 may operate in cooperation with
the system of FIGS. 1 and 2. Additionally, portions of method 300
may be actions taken in the physical world to transform an
operating state of an actuator or device. The method of FIG. 3 may
be incorporated into the system of FIGS. 1 and 2 as executable
instructions stored in non-transitory memory.
[0047] At block 302, accelerator pedal position references a torque
converter turbine torque map 302a to determine a requested torque
converter turbine torque. Block 302 outputs a torque converter
turbine torque request or an amount of torque that is requested at
the torque converter turbine to block 304. Thus, the output of
block 302 is a torque converter turbine that is directly linked to
accelerator pedal position. The accelerator pedal position
references a table or function (e.g., a map) 302a. Table or
function 302a contains and outputs empirically determined values of
torque converter turbine torque. In one example, requested torque
converter turbine torque increases linearly in a 1:1 ratio with
accelerator pedal position so that a 10% deflection in accelerator
pedal position corresponds to 10% of a maximum torque converter
turbine torque. Thus, there may be a linear relationship between
accelerator pedal position and requested torque converter turbine
torque. This relationship may exist whether or not the transmission
is engaged in a gear or in neutral.
[0048] The torque converter turbine torque request, transmission
fluid temperature, and the measured or estimated torque converter
turbine speed are input to block 304 and block 304 outputs a
requested torque converter speed ratio (SR). The actual torque
converter turbine speed, requested torque converter turbine torque,
and transmission fluid temperature reference a table or function
(e.g., a map) 304a (e.g., a torque converter map). The table or
function outputs a requested torque converter speed ratio. The map
or function 304a is an empirical model of a torque converter.
Values in the table or function may be determined via installing
the torque converter in a test stand and monitoring torque
converter speed ratio, torque converter turbine torque, torque
converter turbine speed, and torque converter fluid temperature
(e.g., also referred to as transmission fluid temperature). The
requested torque converter speed ratio is input to block 305.
[0049] At block 305, a requested torque converter impeller speed
(.omega..sub.imp) is determined. The requested torque converter
impeller speed is determined via dividing the requested torque
converter turbine torque .omega..sub.turbine by the torque
converter speed ratio (SR). Block 305 outputs the requested torque
converter impeller speed to block 306.
[0050] At block 306, the torque converter turbine speed is limited
to a speed that is greater than or equal to an engine idle speed.
The torque converter turbine speed is limited to a speed that is
greater than or equal to the engine idle speed so that the engine
may not stall. Block 306 outputs the limited requested torque
converter impeller speed to block 308.
[0051] Block 306 limits a rate of change of the torque converter
impeller speed request. For example, block 306 may prevent the
torque converter impeller speed request from increasing by a rate
that is greater than a predetermined amount (e.g., 200 RPM/second)
so that torque modulation may provide a smooth driveline torque
progression. Block 306 outputs the rate limited torque converter
impeller speed request to summing junction 310.
[0052] At summing junction 310, the actual torque converter
impeller speed is subtracted from the requested torque converter
impeller speed. The result is input to block 312. The result as a
torque converter impeller speed error.
[0053] Block 312 represents a proportional/integral (PI)
controller. Alternatively, block 312 may be a
proportional/integral/derivative (PID) controller. In one example,
the PI controller may be expressed as:
CO=K.sub.pe(t)+K.sub.i.intg.e(t)dt, where CO is the controller
output, K.sub.p is the proportional gain (e.g., a scalar real
number), e(t) is the torque converter impeller speed error with
respect to time (t), and K.sub.i is the integral gain (e.g., scalar
real number). The PI or PID controller operates on the error value
and the output of the PI or PID controller is a requested torque
converter impeller torque. The requested torque converter impeller
torque is input to block 314.
[0054] At block 314, the requested torque converter impeller torque
is limited such that electric machine torque request are limited to
less than a first torque (e.g., 200 Newton-meters) and to greater
than a second torque (e.g., -200 Newton-meters). In other words,
electric machine torque is prevented from exceeding the first
torque and prevented from being less than the second torque. Torque
of electric machine 240, or alternatively the engine 10, is
adjusted such that the electric machine or engine rotates the
impeller speed at a speed that generates the requested torque
converter impeller torque. Torque of the electric machine is
adjusted via adjusting voltage and/or current that is applied to
the electric machine. Torque of the engine is adjusted via
adjusting throttle position and fuel injection timing.
[0055] In this way, speed of an electric machine may be adjusted
via adjusting torque of the electric machine so that the electric
machine rotates a torque converter impeller at a speed that
generates a torque converter turbine torque that is proportionate
and linear with respect to accelerator pedal position. Further,
there is a unique torque converter turbine torque for a given
accelerator pedal position and the relationship between accelerator
pedal position and torque converter turbine torque is linear.
Nevertheless, operating the electric machine in this way may impact
electric energy storage device state of charge. Therefore, method
300 includes a way to balance electric energy storage device state
of charge.
[0056] The actual amount of electric energy storage device
discharge power or the actual amount of discharge power is
determined via monitoring voltage and current that is supplied to
electric machine 240 via electric energy storage device 275. The
actual amount of electric energy storage device discharge power is
input to summing junction 316.
[0057] Accelerator pedal position and state of charge (SOC) of
electric energy storage device 275 are input to block 318. Block
318 includes a table or function (e.g., map) 318a that outputs a
requested electric energy storage device discharge power. The
actual electric energy storage device discharge power amount is
subtracted from the requested electric energy storage device
discharge power amount to generate an electric energy storage
device discharge error. The electric energy storage device
discharge error is output from summing junction 316 to block
322.
[0058] Block 322 represents a proportional/integral (PI)
controller. Alternatively, block 322 may be a
proportional/integral/derivative (PID) controller. In one example,
the PI controller may be expressed as:
CO=K.sub.pe(t)+K.sub.i.intg.e(t)dt, where CO is the controller
output, K.sub.p is the proportional gain (e.g., a scalar real
number), e(t) is the torque converter impeller speed error with
respect to time (t), and K.sub.i is the integral gain (e.g., scalar
real number). The PI or PID controller operates on the electric
energy storage device discharge error and the PI or PID controller
outputs a requested engine torque. The requested engine torque is
delivered to the engine and the engine delivers the requested
engine torque. The requested engine torque may be delivered via
adjusting engine throttle position, fuel injection, and spark
timing.
[0059] In this way, engine torque may be adjusted so that if energy
storage device SOC is low, additional engine torque is requested so
that the electric machine 240 may convert the engine torque into
electric energy that may then be stored in the electric energy
storage device. If energy storage device SOC is high, no engine
torque may be requested and driveline torque may be provided solely
via the electric machine 240.
[0060] Thus, method 300 provides for vehicle operating method,
comprising: generating a torque converter speed ratio in response
to a torque converter turbine torque request, an transmission fluid
temperature, and a measured torque converter turbine speed; and
adjusting a torque of an electric machine via a controller in
response to a requested torque converter impeller speed that is
based on the torque converter speed ratio. The method includes
where the torque of the electric machine is adjusted via a
proportional/integral controller. The method further comprises
determining the requested torque converter impeller speed via
dividing the measured torque converter turbine speed by the torque
converter speed ratio. The method further comprises referencing the
torque converter map via the torque converter turbine torque
request, the transmission fluid temperature, and an actual torque
converter turbine speed to generate the torque converter speed
ratio. The method further comprises generating the torque converter
turbine torque request via a torque converter turbine torque map.
The method further comprises referencing the torque converter
turbine torque map via accelerator pedal position. The method
further comprises limiting a rate of change of the requested torque
converter impeller speed.
[0061] The method of FIG. 2 also provides for a vehicle operating
method, comprising: generating a torque converter speed ratio in
response to a torque converter turbine torque request, an
transmission fluid temperature, and a measured torque converter
turbine speed; adjusting a torque of an electric machine via a
controller in response to a requested torque converter impeller
speed that is based on the torque converter speed ratio; and
adjusting an engine torque in response to an error between a
requested electric energy storage device discharge power and an
actual electric energy storage discharge power. The method includes
where the requested electric energy storage device discharge power
is a function of accelerator pedal position and state of charge of
an electric energy storage device. The method further comprises
applying a proportional/integral controller to the error between
the requested electric energy storage device discharge power and
the actual electric energy storage discharge power. The method
includes where the actual electric energy storage discharge power
is based on adjusting the torque of the electric machine. The
method further comprises adjusting the torque of the electric
machine in response to accelerator pedal position. The method
further comprises adjusting the torque of the electric machine in
response to transmission fluid temperature.
[0062] In another representation, the method of FIG. 3 provides for
a vehicle operating method, comprising: adjusting a speed of an
electric machine via a controller to generate a torque converter
impeller torque that is proportionate to an accelerator pedal
position. The method further comprises determining a torque
converter impeller speed based on accelerator pedal position,
transmission fluid temperature, and actual torque converter turbine
speed. The method further comprises adjusting an engine torque
responsive to an amount of electric power discharged from an
electric energy storage device to the electric machine.
[0063] Referring now to FIG. 4, a prior art vehicle operating
sequence is shown. The plots shown in FIG. 4 are time aligned and
occur at the same time. The vertical lines represent times of
interest during the sequence.
[0064] The first plot from the top of FIG. 4 is a plot of vehicle
speed versus time. The vertical axis represents the vehicle speed
and the vehicle speed increases in the direction of the vertical
axis arrow. The horizontal axis represents time and time increases
from the left side of the figure to the right side of the figure.
Trace 402 represents the vehicle speed.
[0065] The second plot from the top of FIG. 4 is a plot of
accelerator pedal position versus time. The vertical axis
represents the accelerator pedal position and the accelerator pedal
position increases (e.g., is applied further) in the direction of
the vertical axis arrow. The horizontal axis represents time and
time increases from the left side of the figure to the right side
of the figure. Trace 404 represents the accelerator pedal
position.
[0066] The third plot from the top of FIG. 4 is a plot of torque
converter impeller torque versus time. The vertical axis represents
the torque converter impeller torque and torque converter impeller
torque increases in the direction of the vertical axis arrow. The
horizontal axis represents time and time increases from the left
side of the figure to the right side of the figure. Trace 406
represents the torque converter impeller torque.
[0067] The fourth plot from the top of FIG. 4 is a plot of torque
converter turbine torque versus time. The vertical axis represents
the torque converter turbine torque and the torque converter
turbine torque increases in the direction of the vertical axis
arrow. The horizontal axis represents time and time increases from
the left side of the figure to the right side of the figure. Trace
408 represents the torque converter turbine torque.
[0068] The fifth plot from the top of FIG. 4 is a plot of vehicle
axle torque versus time. The vertical axis represents the vehicle
axle torque and the vehicle axle torque increases in the direction
of the vertical axis arrow. Trace 410 represents the vehicle axle
torque. The horizontal axis represents time and time increases from
the left side of the figure to the right side of the figure.
[0069] At time t0, the accelerator pedal is applied a small amount
and vehicle speed is zero. The torque converter impeller torque is
at a lower level and the torque converter turbine torque is at a
lower level. The axle torque is at a lower level.
[0070] At time t1, the human driver applies the accelerator pedal
while the vehicle speed remains zero. The torque converter impeller
torque begins to increase as the accelerator pedal is applied. The
torque converter impeller torque may increase due to an increase in
engine torque or an increase in electric machine torque. The torque
converter turbine torque also begins to increase in response to the
increase in the increase in accelerator pedal position. The axle
torque begins to increase as the torque converter turbine torque
begins to increase.
[0071] Between time t1 and time t2, the vehicle speed remains zero
and the accelerator pedal position is gradually increased via the
driver. The torque converter impeller torque increases gradually
with the increase in accelerator pedal position. Additionally, the
torque converter turbine torque increases at a rate that is greater
than the rate of torque increase of the torque converter impeller
torque due to torque multiplication within the torque converter.
The higher rate of increase in torque converter turbine torque may
make it more difficult for the vehicle's human driver to control
wheel torque. The axle torque increases at a rate that is similar
to the rate of torque converter turbine torque increase.
[0072] At time t2, the driver applies the accelerator pedal a
larger amount to initiate acceleration of the vehicle and the
vehicle begins to accelerate between time t2 and time t3. The
torque converter impeller torque increases as accelerator pedal
position increases. The torque converter turbine torque increases
at an even higher rate, thereby increasing the axle torque more
significantly with smaller increases in accelerator pedal position.
The larger rate of increase in torque converter turbine torque may
help to cause the vehicle's driver to apply the accelerator farther
than may be desired to provide a desired amount of axle torque. The
torque converter output may be non-linear with respect to
accelerator pedal position and engine and/or electric machine
torque. In this example, the driver also releases the accelerator
pedal to slow the vehicle acceleration rate between time t2 and
time t3.
[0073] At time t3, the accelerator pedal position reaches zero
(e.g., fully released) and the torque converter turbine torque is
reduced to a lower value shortly thereafter. The torque converter
impeller torque is also reduced to a lower value and the axle
torque is reduced to a lower value. This behavior may be attributed
to torque converter torque multiplication that is from driveline
inertia and a desire to prevent engine stalling when the
accelerator pedal is fully released. Thus, the torque converter
turbine torque and axle torque may not accurately follow torque
that is requested via the accelerator pedal position. Further,
there is not a consistent torque relationship between accelerator
pedal position and torque converter turbine torque.
[0074] Referring now to FIG. 5, a prophetic vehicle operating
sequence according to the method of FIG. 3 is shown. The vehicle
operating sequence of FIG. 5 may be provided via the system of
FIGS. 1 and 2 in cooperation with the method of FIG. 3. The plots
shown in FIG. 5 are time aligned and occur at the same time. The
vertical lines represent times of interest during the sequence.
[0075] The first plot from the top of FIG. 5 is a plot of vehicle
speed versus time. The vertical axis represents the vehicle speed
and the vehicle speed increases in the direction of the vertical
axis arrow. The horizontal axis represents time and time increases
from the left side of the figure to the right side of the figure.
Trace 502 represents the vehicle speed.
[0076] The second plot from the top of FIG. 5 is a plot of
accelerator pedal position versus time. The vertical axis
represents the accelerator pedal position and the accelerator pedal
position increases (e.g., is applied further) in the direction of
the vertical axis arrow. The horizontal axis represents time and
time increases from the left side of the figure to the right side
of the figure. Trace 504 represents the accelerator pedal
position.
[0077] The third plot from the top of FIG. 5 is a plot of torque
converter impeller torque versus time. The vertical axis represents
the torque converter impeller torque and torque converter impeller
torque increases in the direction of the vertical axis arrow. The
horizontal axis represents time and time increases from the left
side of the figure to the right side of the figure. Trace 506
represents the torque converter impeller torque.
[0078] The fourth plot from the top of FIG. 5 is a plot of torque
converter turbine torque versus time. The vertical axis represents
the torque converter turbine torque and the torque converter
turbine torque increases in the direction of the vertical axis
arrow. The horizontal axis represents time and time increases from
the left side of the figure to the right side of the figure. Trace
408 represents the torque converter turbine torque.
[0079] The fifth plot from the top of FIG. 5 is a plot of vehicle
axle torque versus time. The vertical axis represents the vehicle
axle torque and the vehicle axle torque increases in the direction
of the vertical axis arrow. Trace 510 represents the vehicle axle
torque. The horizontal axis represents time and time increases from
the left side of the figure to the right side of the figure.
[0080] At time t10, the accelerator pedal is applied a small amount
and vehicle speed is zero. The torque converter impeller torque is
at a lower level and the torque converter turbine torque is at a
lower level. The axle torque is at a lower level.
[0081] At time t11, the human driver applies the accelerator pedal
while the vehicle speed remains zero. The torque converter impeller
torque begins to increase as the accelerator pedal is applied. The
torque converter impeller torque may increase due to an increase in
engine torque or an increase in electric machine torque. The torque
converter turbine torque also begins to increase in response to the
increase in the increase in accelerator pedal position. The axle
torque begins to increase as the torque converter turbine torque
begins to increase.
[0082] Between time t11 and time t12, the vehicle speed remains
zero and the accelerator pedal position is gradually increased via
the driver (not shown). The torque converter impeller torque
increases gradually with the increase in accelerator pedal
position. Additionally, the torque converter turbine torque
increases with accelerator pedal position. In particular, there is
torque multiplication between the torque converter impeller torque
and the torque converter turbine torque, but torque converter
turbine torque increases consistently with the increase in
accelerator pedal position. This may allow a vehicle's driver to
operate the vehicle with greater ease. There is a uniform rate of
change in torque converter impeller torque and torque converter
turbine torque. The axle torque increases at a rate that is similar
to the rate of torque converter turbine torque increase since it is
a multiplication of turbine torque by the gear ratio.
[0083] At time t12, the driver applies the accelerator pedal a
larger amount to initiate acceleration of the vehicle and the
vehicle begins to accelerate between time t12 and time t13. The
torque converter impeller torque increases as accelerator pedal
position increases. The torque converter turbine torque increases
similarly with the rate of change in accelerator pedal position. In
this example, the driver releases the accelerator pedal to slow the
vehicle acceleration rate between time t12 and time t13.
[0084] At time t3, the accelerator pedal position reaches zero
(e.g., fully released) and the torque converter turbine torque is
reduced to a lower value shortly thereafter. The torque converter
impeller torque is also reduced to a lower value and the axle
torque is reduced to a lower value. Thus, the torque converter
turbine torque and axle torque may accurately follow torque that is
requested via the accelerator pedal position. Further, there is a
consistent torque relationship between accelerator pedal position
and torque converter turbine torque.
[0085] Referring now to FIG. 6, an example torque converter map is
shown in plot 600. Plot 600 includes a function 304a, which is
shown as a mesh, representing the output of plot 600. Plot 600 is
referenced or indexed via a torque converter speed ratio (e.g.,
SR=torque converter impeller speed/torque converter turbine speed),
torque converter K factor, and transmission fluid temperature. The
vertical axis 650 represents the torque converter speed ratio SR.
Axis 652 represents torque converter K factor, which may be
determined via operation the torque converter in a dynamometer and
monitoring torque converter speeds and torques. Axis 654 represents
transmission fluid temperature and transmission fluid temperature
increases from the origin of plot 600 in the direction of the arrow
of axis 654.
[0086] Mesh 304a shows that the torque converter speed ratio
decreases with increasing transmission fluid temperature. Mesh 304a
also shows that the torque converter speed ratio increases with
decreasing torque converter K factor. The torque converter K factor
represents the torque converter's capacity to transfer torque
across the torque converter. The torque capacity of the torque
converter is lower for lower K factor values.
[0087] Note that the example control and estimation routines
included herein can be used with various engine and/or vehicle
system configurations. The control methods and routines disclosed
herein may be stored as executable instructions in non-transitory
memory and may be carried out by the control system including the
controller in combination with the various sensors, actuators, and
other engine hardware. The specific routines described herein may
represent one or more of any number of processing strategies such
as event-driven, interrupt-driven, multi-tasking, multi-threading,
and the like. As such, various actions, operations, and/or
functions illustrated may be performed in the sequence illustrated,
in parallel, or in some cases omitted. Likewise, the order of
processing is not necessarily required to achieve the features and
advantages of the example embodiments described herein, but is
provided for ease of illustration and description. One or more of
the illustrated actions, operations and/or functions may be
repeatedly performed depending on the particular strategy being
used. Further, at least a portion of the described actions,
operations and/or functions may graphically represent code to be
programmed into non-transitory memory of the computer readable
storage medium in the control system. The control actions may also
transform the operating state of one or more sensors or actuators
in the physical world when the described actions are carried out by
executing the instructions in a system including the various engine
hardware components in combination with one or more
controllers.
[0088] This concludes the description. The reading of it by those
skilled in the art would bring to mind many alterations and
modifications without departing from the spirit and the scope of
the description. For example, I3, I4, I5, V6, V8, V10, and V12
engines operating in natural gas, gasoline, diesel, or alternative
fuel configurations could use the present description to
advantage.
* * * * *